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A linear aperture whose width is 0.02 em is placed immediately in front of a lens of focal length 60 cm. The aperture is illuminated normally by a parallel beam of wavelength 5 xx 10^(-5) cm. The distance of the first dark band of the differation pattern from the centre of the screen is ....... |
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Answer» `0.20` cm `-d sin theta_(m)=m lambda` `:. sin theta_(1)=((1)lambda)/(d)` but `sin theta_(1)=(x_(1))/(D)` `:.(x_(1))/(D)=(lambda)/(d)` `:.x_(1)=(D lambda)/(d)` `=(60xx5xx10^(-5))/(0.02)=0.15 cm` |
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